• Introduction

  • Horizontal well Intervention

  • Geological Setting

  • Tubing Conveyed Openhole Logging

  • Isolation Candidate Selection

  • 1996 Program Review

  • Summary

  • Recommendations

  • Questions

Figure. Williston Basin Setting (Available in full paper)


  • Weyburn Unit is located in the northern portion of the Williston Basin

  • 125 km SE of Regina

Figure. Weyburn Unit Sakskatchewan, Canada (Available in full paper)


  • 22 km long X 18 km wide = 396 square kms

  • 130 horizontal wells with 253 legs

  • 520 vertical producing wells

  • 168 injection wells

  • 1.2 billion barrels of oil in place

Figure. Weyburn Unit - Production History and Forecast (Available in full paper)


  • field discovered in 1954

  • waterflood started in 1963

  • production peaked at about 7500 m3/d

  • vertical infill program in 1980's

  • horizontal pilots in 1991 and 1992

  • horizontal infill program started in 1993 and is still ongoing, the majority of which have been drilled under balanced

  • opportunities identified until the end of 1998

  • the current production is 3500 m3/d

  • horizontal wells account for 19% ofthe producing well count, however, they contribute 65% ofthe total oil production

  • recently announced Canada's largest CO2 miscible flood at Weyburn, injection of CO2 by Q3 1999

Figure. Horizontal well Intervention (Available in full paper)


  • horizontal well technology, especially multi-lateral technology, has outpaced developments in cost effective intervention

  • intervention can mean anything such as stimulations, isolations (mechanical or chemical), logging

  • this project is another step in the development ofa horizontal well intervention strategy that will ensure that PanCanadian is aware ofor involved in development of the technology required to optimize recovery using horizontal wells

  • the downhole environment in Weyburn is severe, H2S ∼5%, high brine and ofcourse will be faced with CO2 in the future

  • all interventions must be compatible with the above

  • 130 horizontal wells, 70% ofwhich are multi-lateral, with approximately 250 km of openhole section

  • one small interval in a horizontal well that is in communication with the under lying Vuggy can be the dominant producing feature ofthe well

  • quad wells have 4000 m ofopenhole section; where do we start looking? - only source ofinformation is fluids and pressure while drilling

  • objective ofthis project was to isolate these highly conductive zones so that the well could be pumped down with the existing lift equipment

  • for other projects this type of intervention could be used to reduce operating costs or to reduce voidage requirements when infrastructure constraints become apparent

  • if intervention is impportant under waterflood it is critical under miscible flood

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